Apparatus and a method for stranding a twisted unit of a cable

ABSTRACT

For SZ stranding, the stranding elements which remain united in the stranding or twisted unit are led in a stretched twisted condition to a twisting device which twists the twisted unit in sections, each of a multiple of stranding strokes. The twisting device is positioned closer to the takeup point than to the payout point of the twisted unit. A longitudinal section of the twisted unit has a minimum length equal to the distance between the takeup point and the twisting device and a maximum length equal to three times the distance between the twisting device and the payout point.

United States Patent Inventors Wolfgang Feese Berlin; Heinz Oberender;Heinz Badura, Nenstadt/Colburg, all 01', Germany Appl. No. 825,647 FiledMay 19, 1969 Patented July 20, 1971 Assignee Siemens AktiengesellschaftBerlin, Munich, Germany Priority May 21, 1968 Germany P 17 65 452.3

APPARATUS AND A METHOD FOR STRANDING A TWISTED UNIT OF A CABLE 23Claims, 8 Drawing Figs.

U.S.Cl. 57/34 AT, 57159, 57/156 lnt.Cl. ..ll0lb 13/02 Field otSearch57/34,59, 34 AT, 60, 156,3, 12, 160, 62

Primary Examiner.lohn Petrakes Attorneys-Curt M. Avery, Arthur E.Wilfond, Herbert L.

Lerner and Daniel J. Tick ABSTRACT: For SZ stranding, the strandingelements which remain united in the stranding or twisted unit are led ina stretched twisted condition to a twisting device which twists thetwisted unit in sections, each of a multiple of stranding strokes. Thetwisting device is positioned closer to the takeup point than to thepayout point of the twisted unit. A longitudinal section of the twistedunit has a minimum length equal to the distance between the takeup pointand the twisting device and a maximum length equal to three times thedistance between the twisting device and the payout point.

PATENTED JUL20 m sum 1 OF 4 Fig. 1

IQQ' 4 Fig. 2

APPARATUS AND A METHOD FOR STRANDING A TWISTED UNIT OF A CABLEDESCRIPTION OF THE INVENTION The present invention relates to apparatusand a method for stranding a twisted unit of a cable. More particularly,the invention relates to apparatus and a method for stranding a twistedunit of a cable in different directions of stranding for individuallengths.

Recent technical development in the manufacture of common cables isconnected with the concentration of stranding or twisting operationswhich have previously been undertaken separately. These operations are,for example, stranding or twisting of basic units and main units intoone work operation in order to enhance efficiency. For this purpose,stranding processes are required to assist the stranding of the twistedunits. Each twisted unit comprises a plurality of twisted elements. Thetwisted units are stranded or twisted alternately with a left-hand layor S-twist and a right-hand lay or Z-twist in continuous lengths. Allstranding or twisting of this type, known as oscillated twisting, andlately known as S2 twisting, has the advantage that the elements to betwisted may be paid out from stationary supply sources and that furtherprocessing of the twisted unit, which is formed by twisting suchelements, may be undertaken immediately after twisting during the samework operation utilizing the S2 twisting process.

Heretofore, as a rule, the proposed or known processes for S2 twistinghave utilized rotating cradles having a twofold function. These cradlesfunction simultaneously as take up containers for storing the twistedunit and pay out containers for supplying the elements. During thisprocess, the direction of stranding or twisting must be rotary atintervals in accordance with the lengths in the cradles.

A device described in German Pat. No. DAS 1,197,144 for strandingtelephone cables operates without the aforedescribed cradles. in suchwell-known device, the wire pairs pulled from stationary payout reels ingroups are led through a single oscillating disc each. The oscillatingdiscs swing back and forth or oscillate in alternating sequence therebyturning alternately in one direction and then in the other. Theoscillating twisting or stranding discs may not, however, be turned bymore than :l80. If the oscillating discs were turned by more than 180,the wire groups would twist too much in front of said discs and thepretwisted elements pulled against the oscillating discs when they aremoved from the payoff reels would break off or be damaged. The max imumphase angle of twist thus remains small. Furthermore, the twistsattained have proven to be insufficient for electrical decoupling of thetwisted elements of telephone cables.

The principal object of the present invention is to provide a new andimproved process and apparatus for stranding a twisted unit of a cablein different directions of stranding for individual lengths.

An object of the present invention is to provide a process and apparatusfor stranding a twisted unit of a cable in different directions ofstranding with rapidity, efficiency, effectiveness and reliability.

An object of the present invention is to provide a process and apparatusfor stranding a twisted unit of a cable in different directions ofstranding, which process and apparatus overcome the disadvantages ofknown processes and apparatus of similar type.

An object of the present invention is to provide apparatus of simplestructure for stranding a twisted unit of a cable in differentdirections of stranding.

In accordance with the present invention, a twisted unit of a cable suchas, for example, a communication cable comprising a plurality ofelements, is stranded with different twisting directions for eachsection. The elements of the twisted unit are led to a stationary payoutpoint at which the twisted unit is formed from such elements. Thetwisted unit is then led from the payout point to a twisting device in aswitched rotatable condition perpendicular to the axis of the twistedunit. The twisting device grasps the twisted unit and turns said twistedunit by a multiple of twists sectionwise between the payout point and astationary takeup point at which a different twist of the twisted unitis provided sectionwise. The distance between the takeup point and thepoint at which the twisting device grasps the twisted unit is smallerthan the distance between the point at which the twisting device graspsthe twisted unit and the payout point. A single length section'havingthe same twist direction of the twisted unit has a minimum length equalto the distance between the takeup point and the point at which thetwisting device grasps the twisted unit and a maximum length equal tothree times the distance between the point at which the twisting devicegrasps the twisted unit and the payout point.

The process and apparatus of the present invention insures that eachlength section of the twisted unit having a different direction oftwisting is provided with a sufficient number of twists, whereassimultaneously the periodic variation in the direction of twistingand/or the speed of the twisting device is undertaken so rapidly thatany significant decrease in the turning of the length section of thetwisted unit passing through the twisting device, resulting from theoperation of the twisting device because of the twisted unit approachingtoo close to the buildup condition, is avoided. The twisted unit istwisted between the payout point and the point at which the twistingdevice grasps the twisted unit. Only a portion of the twisted unit mayslip through the twisting device during the process.

If the direction of rotation of the twisting device remains the same,the twisting of the twisted unit increases continuously between thepayout point and the point at which the twisting device grasps thetwisted unit. Thus, if the speed of the twisting device remainsconstant, an equilibrium condition occurs between the twisting of thetwisted unit led to the twisting device and the twist per length sectionprovided by the twisting device. In this case, the torsion of the partof the twisted unit in front of the twisting device would attain an endvalue. However, the twisting of the part of the twisted unit in thepulloff direction behind the twisting device would be equal to zero.

The apparatus and method of the present invention are based upon theconception that the end value is provided by the uniformity of twistingprovided per length section by the twisting device on one hand, and thetwisting of the twisted unit led to the twisting device on the otherhand. The invention is also based on the conception that up to theinstant the end value is reached, the length section of the twisted unitpassing through the twisting device is provided with a twist in the samedirection. Before the end value is reached, a new end value is providedby changing the direction of rotation and/or speed of the twistingdevice. Twisting of the twisted unit is then continued to a laterinstant before the new end value is reached.

In the apparatus of the present invention, the distance between thetakeup point and the point of engagement of the twisting device with thetwisted unit is made essentially shorter than the distance between thepoint of engagement of the twisting device with the twisted unit and thepayout point. This results in an extraordinarily high degree ofefficiency, so that a relatively small speed of the twisting device issufficient to guarantee adequate twisting of the twisted unit led to thetakeup point. The relation between the distance between the takeup pointand the point of engagement of the twisting device with the twisted unitand the distance between the point of engagement of the twisting devicewith the twisted unit and the payout point is varied continuously or instages during the twisting process.

In accordance with the present invention, apparatus for stranding atwisted unit of a cable in different directions of stranding forindividual lengths comprises a plurality of cable elements. A fixedpayout point forms a twisted unit from the cable elements. A twistingdevice engages the twisted unit in a nonpositive manner perpendicular tothe axis of the twisted unit. The twisted unit is led to the twistingdevice in stretched rotatable condition. The twisting device rotates thetwisted unit a number of twists between the payout point and the takeuppoint and provides a different direction of stranding of the twistedunitfor individual section lengths. The twisting device engages thetwisted unit at a point closer to the takeup point than to the payoutpoint. A section of the twisted unit having the same direction ofstranding has a minimum length which is the length between the takeuppoint and the engagement point of the twisting device and a maximumlength which is three times the length between the engagement point andthe payout point.

The twisting device is positioned as close as possible to the takeuppoint.

The twisted unit is stranded at the takeup point and one of the speedand direction of rotation of the twisting device is regulated inaccordance with the stranding of the takeup point during the passagethrough the twisting device of a section of the twisted unit having thesame direction of stranding. The regulation of the one of the speed anddirection of rotation provides stranding which is as constant aspossible over the entire section of the twisted unit having the samedirection of stranding. A stranding device is provided between thetwisting device and the takeup point for stranding a plurality oftwisted units. The regulation of the one of the speed and direction ofrotation provides resultant stranding of the stranding device of uniformsize and length.

The speed of the twisting device is increased during the passage throughthe twisting device of a section of the twisted unit having the samedirection of stranding. The speed of the twisting device is variedduring the passage through the twisting device of a section of thetwisted unit having the same direction of stranding.

The twisting device rotates in a single direction during twisting of thetwisted unit. The twisting device rotates intermittently in a singledirection during twisting of the twisted unit. The twisting device isrotated after reaching a specific minimum during the stranding of thesection of the twisted unit. The twisting device is rotated and engagesin a nonpositive manner a length of twisted unit perpendicular to theaxis of the twisted unit preventing spreading thereof. The length ofengaged twisted unit is shorter than the length of twisted unit to betwisted in the direction of rotation of the twisting device. Thetwisting device comprises spaced components on both sides of the twistedunit and the components contact the twisted unit with a pressure whichdoes not hinder the passage of the twisted unit through the twistingdevice. The twisting device functions as a lever relative to the axis ofthe twisted unit and transfers force to the twisted unit in thedirection of rotation of the twisting device by deflection of thetwisted unit. The twisting device comprises three spaced rollers mountedfor coplanar rotation with their axes positioned in a manner whereby thetwisted unit passes in contact with each of the rollers in curvilinearfashion.

An additional twisting device between the payout point and the twistingdevice provides homogeneous stranding of the section of the twisted unitbetween the payout point and the twisting device. The twisting deviceand the additional twisting device rotate in the same direction atincreasing speeds relative to the advancing of the twisted unit.

In accordance with the present invention, a process for stranding atwisted unit of a cable in different directions of stranding forindividual lengths comprises the steps of forming a twisted unit from aplurality of cable elements at a payout point and twisting the twistedunit in a nonpositive manner perpendicular to the axis of the twistedunit a number of twists at a point between the payout point and a takeuppoint and providing a different direction of stranding of the twistedunit for individual section lengths when the twisted unit is instretched rotatable condition at a point closer to the takeup point thanto the payout point. A section of the twisted unit having the samedirection of stranding has a minimum length which is the length betweenthe takeup point and the twisting point and a maximum length which isthree times the length between the twisting point and the payout point.

The distance between the takeup point and the twisting point isconsiderably smaller than the distance between the twisting point andthe payout point. The relation of the distance between the takeup pointand the twisting point and the distance between the twisting point andthe payout point is varied.

The process further comprises the step of stranding a plurality oftwisted units, each twisted by twisting a correspond ing one of aplurality of twisted units. Each of the twisted units is twisted at avarying one of speed and direction of rotation. The variation oftwisting occurs at a time different from that of the others. Each of thetwisted units is twisted at a different one of speed and direction ofrotation from that of the others. Each of the twisted units is twistedat a twisted point a distance from a corresponding takeup point and adistance from a corresponding payout point which have a differentrelation to each other from the others.

In order that the present invention may be readily carried into effect,it will now be described with reference to the accompanying drawings,wherein:

FIG. 1 is a schematic diagram of an embodiment of the apparatus of thepresent invention for performing the process of the present invention;

FIG. 2 is a graphical presentation of the stranding process of thepresent invention;

FIG. 3 is a schematic diagram of another embodiment of the apparatus ofthe present invention;

FIG. 4 is a schematic diagram of another embodiment of the apparatus ofthe present invention;

FIG. 5 is a schematic diagram of an embodiment of a twisting device;

FIG. 6 is a schematic diagram of another embodiment of a twistingdevice;

FIG. 7 is a schematic diagram of another embodimentof a twisting device;and

FIG. 8 is a top view of the twisting device of FIG. 7.

In the FIGS., the same components are identified by the same referencenumerals.

The basic unit of a communication cable having unit-type design isassumed to be the twisted unit. The twisted unit comprises elements orstrands 2. As shown in FIG. I, a plurality of payout stands or sourcesprovide the elements or strands 2. In FIG. 1, five strands 2 are led toa payout point E. A nipple 9 at the payout point E combines the fiveelements 2 into a basic twisted unit 1.

The twisted or basic unit 1 is led to a twisting device 4 in a stretchedrotatable or twisted condition. The twisting device 4 engages thetwisted unit 1 perpendicularly to the axis of said twisted unit in anonpositive manner. The twisted unit 1 is then led in the direction ofthe arrow to the takeup point A where it is wound on a take up reel 5.The takeup point A is determined so that it fixes the different twistingdirections of the twisted unit 1 sectionwise.

In accordance with the present invention, the distance bbetween thetakeup point A and the point of engagement of the twisting device 4 withthe twisted unit 1 is smaller than the distance a between the point ofengagement of twisting device 4 with the twisted unit and the payoutpoint E. In accordance with the present invention, the relation azb isgenerally greater than 5, although satisfactory results have beenobtained with a ratio a:b=5. The greater the ratio azb, the greater theefficiency. In practical operation, the following values have proven tobe suitable.

Fl 0 meters b=0.3 meter Other suitable values are:

Fl 8 meters b=0.5 meter If the twisting device 4 rotates in the samedirection ata specific speed, the part of the twisted unit 1 between thetakeup point A and said twisting device is twisted in one direction andthe part between the payout point E and the twisting device 4 is twistedin the opposite direction. Since the twisted unit I also moves throughthe twisting device 4 at a definite speed of advance, as a result of therotation of the takeup reel 5, part of the twisting provided between thepayout point B and the twisting device 4 on the twisted unit 1continuously slips through the said twisting device, so that twisting ofsaid twisted unit at the takeup point A does not increase proportionallywith the speed of rotation of said twisting device.

Twisted units of cable such as, for example, the twisted unit I, aregenerally not ideally elastic as far as torsion is concerned. Thus,twisting of the part of the twisted unit 1 between the payout point Eand the twisting device 4 is nonhomogeneous. This nonhomogeneouscondition is dependent upon the makeup and, particularly, on thediameter of the twisted unit 1. When the twisted or basic unit 1comprises five elements or strands, as assumed for the illustration ofthe present invention, nonhomogeneous conditions have occurred when thedistance or length a is greater than 5 meters.

For the aforementioned reasons, the twisting of the twisted unit 1 atthe take up point A is not constant, in accordance with the presentinvention. This is explained in FIG. 2 by indicating the length I as theabscissa and indicating the twisting as the ordinate. The curve of FIG.2 is for a wire pair twisted in accordance with the SZ twisting process,utilizing the apparatus of FIG. 1.

The following values were chosen for the distances a and b, the speed ofrotating n of the twisting device 4 and the speed of advance v of thetwisted unit I:

a=5 meters b=l meter n=l 000 r.p.m.

#20 meters per minute The direction of rotation of the twisting device 4was changed at intervals L of IO meters.

As indicated by the twisting values 0 in FIG. 2, the twisting within alength L is n the same direction and increases initially to its maximumvalue and then decreases gradually to its minimum value. The directionof rotation of the twisting device 4 is therefore reversed in sufficienttime before reaching the buildup state, which buildup state means atwisting value 0 equal to zero.

It is advantageous to provide an additional stranding operation in thesame work operation immediately succeeding the process of the presentinvention. In order to achieve this, a plurality of twisted units aretwisted in a plurality of parallel operations in the S2 twisting processin a single continuous operation to the next successive stranding stagein accordance with the present invention.

FIG. 3 illustrates apparatus for twisting a common cable. The strands orelements 2 and 2' are led from stationary supply stands or sources (notshown in FIG. 3) to corresponding nipples 9, 9, and so on, in groups offive strands. Each of the nipples 9, 9, and so on, forms a twisted orbasic unit 1 which is then wound by an open holding helix with theassistance of a spinner 8, 8 and so on. The twisted units 1, l, and soon, are led to a stranding point via guide pulleys 2], 21, and so on,and twisting devices 4, 4, and so on. A nipple is positioned at thestranding point. The nipple 10 combines the twisted units 1, I, and soon, into a main unit 7. The main unit 7 is wound on the takeup reel 5'in a stranding yoke 6.

The twisted units 1, 1, and so on, of which only the twisted units 1 andl are shown in FIG. 3 in order to enhance the clarity of illustration,pass through the corresponding twisting devices 4, 4, and so on, ofwhich only the twisting devices 4 and 4 are shown in FIG. 3, beforebeing led to the nipple I0. The twisted units I are stranded or twistedbetween the nipples 9, 9', and so on, where they are formed from theelements or strands 2, and the nipple 10 which strands or twists thetwisted units 1, 1, and so on, into the main unit 7, by periodicvariation of the speed and/or direction of rotation of the twistingdevices 4, 4, and so on. The twisting devices 4, 4', and so on, arepositioned as close as possible to the nipple 10. As a result of theperiodic variation of the speed and/or direction of the twisting devices4, 4', and so on, the twisted units 1, l, and so on, are led to thenipple l0with a specific type of stranding. After the twisted units 1,l, and so on, have passed through the nipple 10, the influence of thetwisting devices 4, 4, and so on, on the additional stranding ortwisting of said twisted units is eliminated by the stranding of saidtwisted units into the main unit 7.

In the same manner as illustrated by FIG. 3 for the stranding of a mainunit of a common cable formed of elements and twisted units, it ispossible to twist or strand wire groups comprising, for example, wirepairs. In such a case, the twisting device twists the wire groupscomprising wire pairs before the wire pairs are led to the nipple whichtwists them, in the same work operation.

During the stranding or twisting of a cable in which a plurality oftwisted units are stranded in parallel work operations to the nextsucceeding or next higher stranding stage in the same work operation, inaccordance with the process of the present invention, the speed and/ordirection of rotation of the twisting device of each of the parallelwork operation apparatus may be varied or changed at a time differentfrom that of the others. This insures electrical decoupling of thetwisted units strained together. This may also be achieved by operatingthe twisting devices of the parallel work operation apparatus at speedsand/0r directions of rotation which are different from each other.

In the apparatus of each of the parallel work operations, the distancebetween the takeup point of the twisted unit and the point of engagementof the twisting device with the twisted unit and/or the distance betweenthe point of engagement of the twisting device with the twisted unit andthe payout point of the twisted unit may be selected differently.

As hereinbefore described, with reference to FIG. 2, stranding in theindividual lengths L of a twisted unit is not constant in the process ofthe present invention. It is, however, often desired that stranding ortwisting be as constant as possible within the sequential length of atwisted unit. To attain this, the speed or, if necessary, the directionof rotation, of the twisting device may be regulated during the time inwhich a length of the twisted unit, in completed condition having thesame direction of lay in accordance with the stranding, is provided atthe takeup point. The speed of the twisting device may be increasedcontinuously, for example, or in stages, while a length of a twistedunit having the same stranding direction passes through said twistingdevice. It is, however, also possible to vary the speed of advance whilea length of the twisted unit having the same stranding direction ispassing through the twisting device.

The switching or energization of the twisting device may be delayedafter the periodic variation in the speed and/or direction of rotationof said twisting device has commenced, so that the stranding or twistingwhich has accumulated in front of said twisting device in the directionof advance of the twisted unit may gradually diminish.

The regulation of the speed and, if necessary, the direction of rotationof the twisting device may be provided in a manner whereby during theperiod that a length of the twisted unit having the same direction ofstranding is passing through the twisting device, stranding is asconstant as possible over said entire length of the twisted unit. It isalso possible to provide speed or direction of rotation regulation in amanner whereby the resultant combined stranded units such as, forexample, the main units, each of which comprises a plurality of twistedunits, are as equal to each other as possible in size in each section.In order to provide stranding with reversed directions of stranding insuccessive sections of the twisted unit, the direction of rotation ofthe twisting device may be reversed at periodic reversal points, thatis, after a length L of the twisted -unit has passed through thetwisting device. It is also possible to rotate the twisting device inonly one direction during twisting of the entire twisted unit. In such acase, it is advisable to rotate the twisting device intermittently inthe same direction.

It is preferable that the length of the twisted unit positioned betweenthe payout point B and the twisting device 4 does not become torsionfree. If such length of the twisted unit does not become torsion free, asufficient compactness of the elements 2 forming the twisted unit 1 isinsured. It is therefore advisable, for practical reasons, that thedrive of the twisting device be switched on again after a specificminimum length of the twisted unit 1 between the twisting device 4 andthe payout point E has been reached.

If the twisting device 4 rotates counterclockwise, for example, thesection of the twisted unit is twisted to the right in front of saidtwisting device and the section of said twisted unit behind saidtwisting device is twisted to the left in accordance with the change inthe right-hand twist. If the twisting device is then deenergized orstopped, the section of the twisted unit having the right-hand twistslips through said twisting device unaltered. In this way, the sectionof the twisted unit behind the twisting device in the direction ofadvance toward the take up point A, has a right-hand twist. At the sametime, the righthand twist of the section in front of the twisting deviceis decreased. The decrease in the right-hand twist is interrupted,however, at the proper instant by the reenergization or restarting ofthe twisting device. The twisting device then rotates again to the rightand again increases the right-hand torsion in the section of the twistedunit in front of said twisting device, thereby providing a left-handtorsion behind said twisting device. The constant torsion in the sectionbetween the payout point E and the twisting device continuously holdsthe elements together in the twisted unit. This insures a smoothadmanner without spreading said'tivisted unit perpendicularly to itsaxis by the portions of the twisting device which are shorter than thelength of said twisted unit in the direction in which said twistingdevice is rotated. This means that positive contact only existsperpendicularly to the axis of the twisted unit between the twistingdeviceand said twisted unit, whereas said twisted unit is not hinderedin thedirection of its axis, independently of the effected twisting.Consequently, the stranding or twisting of the twisted unit alreadyprovided in front of the twisting device has no effect on the tensilestress and on the length of the twisted unit advancing through saidtwisting device and having the same direction of rotation.

The transfer of force from the twisting device to the twisted unit inthe direction of rotation of said twisting device is executedadvantageously by contact pressure which does not influence the passageof said twisted unit to any great extent. Thus, for example, two rollersmay be positioned perpendicularly to the axis of the twisted unit andmay be utilized for this purpose. The rollers may be in contact with thetwisted unit positioned between them and may be elastically urged towardvance of the twisted unit so that, if desired, the speed of advance maybe increased. Furthermore, the smooth advance of the twisted unitis'favorable to electrical decoupling of said twisted unit.

In another embodiment of the apparatus of the present invention,additional twisting devices, besides the twisting device 4, are providedbetween the payout point E and the twisting device 4. The additionaltwisting devices support the formation of a homogeneous stranding of thesection of the twisted unit between the initial twisting device 4 andthe pay out point E. In this manner, nonhomogeneous properties of thestranding due to lack of torsional elasticity of the twisted unit areavoided in those cases where the distance a between the twisting device4 and the payout point E in FiG. I is relatively long.

The embodiment of the present invention utilizing additional twistingdevices is illustrated in FIG. 4. The embodiment of FIG. 4 is amodification of the embodiment of FIG. 1. In FIG. 4, additional twistingdevices 42 and 43 are positioned between the initial twisting device 4and the payout point B. Thus, the additional twisting devices 42 and 43are distributed over the distance a. The twisting devices 42 and 43support stranding of the section of the twisted unit 1 between theinitial twisting device 4 and the payout point point E. This results inthe provision of an extension of the freely twistable section of thetwisted unit 1.

The additional twisting devices 42 and 43 need not be evenly spaced inthe distance a. 0n the contrary, as indicated in FIG. 4, the additionaltwisting devices 42 and 43 may be unevenly spaced between the initialtwisting device 4 and the payout point E.

In order to insure homogeneous stranding of the twisted unit I, it ispreferable to permit the speeds of the twisting devices 42, 43 and 4 toincrease in the same direction of rotation with reference to thedirection of advance of the twisted unit 1. The utilization of suitablegearing permits a single drive for all of the twisting devices 4, 42 and43. The gearing may be particularly simple if all the twisting devicesare rotated and are driven intermittently during the entire strandingprocess of the twisted unit I.

In accordance with the present invention, it is preferable that a lengthof the twisted unit 1 be engaged in a nonpositive each other. Therollers are rotated about the axis of the twisted unit.

FIG. 5 illustrates a pair of rollers functioning as a twisting device.The twisted unit 1 comprises a plurality of elements 2, as provided inthe embodiment of FIG. 1, for example. The twisting device of FIG. 5comprises two rollers 38 and 39 coplanarly positioned opposite eachother in a plane perpendicular to the axis of the twisted unit 1. Aspring 40 is affixed at one end to the rotary shaft of the roller 38 andis afi'rxed at its outer end to the rotary shaft of the roller 39. Thespring 40 functions to urge the rollers 38 and 39 toward each otherelastically and thereby urges said rollers into elastic contact with thetwisted unit 1. Each of the rollers 38 and 39 has a peripheral groove orchannel formed around its circumference and the twisted unit 1 fits intosaid channels or grooves.

The rollers 38 and 39 are rotated about the axis of the twisted unit 1,which twisted unit is advanced to the left, so that the twisting devicecomprising said rollers is rotated due to the stranding of said basicunit. It is of primary importance that the contact pressure of therollers 38 and 39 on the twisted unit I resulting from the force of thespring 40 does not practically hinder the passage of said twisted unitthrough the twisting device.

Another advantage of the twisting device is that the transfer of forcefrom said twisting device to the twisted unit is provided in thedirection of rotation of said twisting device via a deflection of saidtwisted unit which functions as a lever relative to its axis. Thetwisting device includes guide elements fixed by the direction ofadvance. FIG. 6 illustrates such a twisting device.

In FIG. 6, the twisted unit 1 is advanced in the direction of the arrow,toward the left, around a roller 41. The roller 41 has a peripheralgroove or channel formed in its circumference to accommodate the twistedunit 1 and is mounted for rotation on a rotary shaft positionedperpendicularly to the axis of the twisted unit 1. The roller 41 isrotated about the axis of the twisted unit 1 determined by the directionof advance of said twisted unit so that said twisted unit is stranded.

FIGS. 7 and 8 illustrate an embodiment of a twisting device which hasproven to be especially adaptable and suitable in field tests. In thetwisting device of FIGS. 7 and 8, the transfer of force is effected by adeflection of the twisted unit functioning as a lever. In this case, thetwisting device comprises three rollers 30, 31 and 32 coplanarlypositioned. The rollers 30, 31

and 32 are mounted with their axes so positioned that the twisted unit 1passes between them in a waving fashion.

Each of the rollers 30, 31 and 32 has a peripheral groove or channelformed around its circumference to accommodate the twisted unit 1. Inthe illustration of FIGS. 7 and 8, the axis of the roller 31 ispositioned between and beneath the axes of the rollers 30 and 32, sothat the twisted unit passes between said rollers in a manner wherebysaid twisted unit is above the roller 31 and beneath the'rollers 30 and32. Any suitable number of rollers may be utilized.

- The twisting device is mounted on a stationary or fixed frame 12 via aroller bearing 11. A flange 27 is fitted onto the rotatable peripheralpart of the roller bearing 11 and is affixed to a disc 28 whichfunctions as a chain or drive wheel. The disc 28 may thus be driven viathe flange 27 in any direction of rotation and at any desired speed viaa drive chain, belt, or the like.

A support member 29 supports the three rollers 30, 31 and 32 which aremounted thereon. The support member 29 is affixed to the disc 28. Thetwisted unit 1 is deflected between the rollers 30 and 32, since itpasses between said rollers and the roller 31 in a waving fashion, sothat a leverlike force is produced perpendicularly to said twisted unit;said twisted unit being engaged by the three rollers of the twistingdevice and being thereby twisted or stranded.

It is preferable to fasten the roller support members to the frame ofthe apparatus with adjusting screws so that the diameter of the twistedunit 1 to be stranded may be correspondingly adjusted. A furtherimprovement is to cover the guiding channels or grooves of the rollers,which contact the twisted unit 1, with elastic material such as, forexample, rubber. It is also advisable to flute the guiding channels orgrooves of the rollers, preferably in V-shaped configurationcorresponding to the diameter of the twisted unit 1. The surfaces of theguiding channels or grooves of the rollers may also be provided withmutually parallel grooves parallel to the axis of the twisted unit, suchgrooves being considerably smaller than half the diameter of an elementof said twisted unit.

The guide rollers utilized to transfer force in the direction ofrotation of the twisting device may additionally be rotated about theiraxes. This facilitates the passage of the twisted unit 1 to be strandedthrough the twisting device.

While the invention has been described by means of specific examples andin specific embodiments, we do not wish to be limited thereto forobvious modifications will occur to those skilled in the art withoutdeparting from the spirit and scope of the invention.

We claim:

1. Apparatus for stranding a twisted unit of a cable in differentdirections of stranding for individual lengths, comprisin i plurality ofcable elements;

a fixed payout point for forming a twisted unit from said cableelements;

a takeup point; and

twisting means engaging said twisted unit in a nonpositive mannerperpendicular to the axis of said twisted unit, said twisted unit beingled to said twisting means in stretched rotatable condition, saidtwisting means rotating said twisted unit a number of twists betweensaid payout point and said takeup point and providing a differentdirection of stranding of the twisted unit for individual sectionlengths, said twisting means engaging said twisted unit at a pointcloser to said takeup point than to said payout point, a section of saidtwisted unit having the same direction of stranding having a minimumlength which is the length between said takeup point and the engagementpoint of said twisting means and a maximum length which is three timesthe length between said engagement point and said payout point.

2. Apparatus as claimed in claim 1, wherein said twisting means ispositioned as close as possible to said takeup point.

3. Apparatus as claimed in claim 1, wherein said twisted unit isstranded at said takeup point and one of the speed and direction ofrotation of said twisting means is regulated in accordance with thestranding at said takeup point during the passage through said twistingmeans of a section of said twisted unit having the same direction ofstranding.

4. Apparatus as claimed in claim 3, wherein the regulation of said oneof said speed and direction of rotation provides stranding which is asconstant as possible over said entire section of said twisted unithavin'gThe same direction of stranding.

5. Apparatus as claimed in claim 3, further comprising stranding meansbetween said twisting means and said takeup point for stranding aplurality of twisted units, and wherein the regulation of said one ofsaid speed and direction of rotation provides resultant stranding ofsaid stranding means of uniform size and length.

6. Apparatus as claimed in claim I, wherein the speed of said twistingmeans is increased during the passage through said twisting means of asection of said twisted unit having the same direction of stranding.

7. Apparatus as claimed in claim I, wherein the speed of said twistingmeans is varied during the passage through said twisting means of asection of said twisted unit having the same direction of stranding.

8. Apparatus as claimed in claim 1, wherein said twisting means rotatedin a single direction during twisting of said twisted unit.

9. Apparatus as claimed in claim 1, wherein said twisting means rotateintermittently in a single direction during twisting of said twistedunit.

10. Apparatus as claimed in claim 1, wherein said twisting means isrotated after reaching a specific minimum during the stranding of thesection of the twisted unit.

11. Apparatus as claimed in claim 1, wherein said twisting means isrotated and engages in a nonpositive manner a length of twisted unitperpendicular to the axis of said twisted unit preventing spreadingthereof, the length of engaged twisted unit being shorter than thelength of twisted unit to be twisted in the direction of rotation ofsaid twisting means.

12. Apparatus as claimed in claim 11, wherein said twisting meanscomprises spaced components on both sides of said twisted unit and saidcomponents contact said twisted unit with a pressure which does nothinder the passage of said twisted unit through said twisting means.

13. Apparatus as claimed in claim 12, wherein said twisting meansfunctions as a lever relative to the axis of said twisted unit andtransfers force to said twisted unit in the direction of rotation ofsaid twisting means by deflection of said twisted unit.

14. Apparatus as claimed in claim 1, further comprising additionaltwisting means between said payout point and said twisting means forproviding homogeneous stranding of the section of said twisted unitbetween said payout point and said twisting means.

15. Apparatus as claimed in claim 14, wherein said twisting means andsaid additional twisting means rotate in the same direction atincreasing speeds relative to the advancing of said twisted unit.

16. Apparatus as claimed in claim 15, wherein said twisting meanscomprises three spaced rollers mounted for coplanar rotation with theiraxes positioned in a manner whereby said twisted unit passes in contactwith each of said rollers in curvilinear fashion.

17. A process for stranding a twisted unit of a cable in differentdirections of stranding for individual lengths, comprising the steps offorming a twisted unit from a plurality of cable elements at a payoutpoint; and

twisting the twisted unit in a nonpositive manner perpendicular to theaxis of said twisted unit a number of twists at a point between thepayout point and a takeup point and providing a different direction ofstranding of the twisted unit for individual section lengths when saidtwisted unit is in stretched rotatable condition at a point closer tothe takeup point than to the payout point, a section of the twisted unithaving the same direction of stranding having a minimum length which isthe length between the takeup point and the twisting point and a maximumlength which is three times the length between the twisting point andthe payoutpoint.

18. A process as claimed in claim 17, wherein the distance between thetakeup point and the twisting point is considerably smaller than thedistance between the twisting point and the payout point.

19. A process as claimed in claim 17, wherein the relation of thedistance between the takeup point and the twisting point and thedistance between the twisting point and the payout point is varied.

20. A process as claimed in claim 17, further comprising stranding aplurality of twisted twisted units, each twisted by twisting acorresponding one of a plurality of twisted units.

21. A process as claimed in claim 20, wherein each of the twisted unitsis twisted at aiiafyfifg one of speed and direction of rotation, thevariation of twisting occurring at a time different from that of theothers.

22. A process as claimed in claim 20, wherein each of the twisted unitsis twisted at a different one of speed and direction of rotation fromthat of the others.

23. A process as claimed in claim 20, wherein each of the twisted unitsis twisted at a twist point a distance from a corresponding takeup pointand a distance from a corresponding payout point which have a differentrelation to each other from the others.

I MR 1 l s M23 UMTED s'wmzs PATENT OFFICE CERTIFICATE OF CORRECTIONPatent No. 3 593 5 9 1 Dated y 20, 97

I g Wolfgang Feese, Heinz Oberender and Heinz Badure It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

. In the address of the second and third inventors, the name of the townshould read --Neustadt/Coburg-- Signed and sealed this 8th day ofFebruary 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. Q RT GOTTSCHALK Attesting Officer Commissioner ofPatents

1. Apparatus for stranding a twisted unit of a cable in differentdirections of stranding for individual lengths, comprising a pluralityof cable elements; a fixed payout point for forming a twisted unit fromsaid cable elements; a takeup point; and twisting means engaging saidtwisted unit in a nonpositive manner perpendicular to the axis of saidtwisted unit, said twisted unit being led to said twisting means instretched rotatable condition, said twisting means rotating said twistedunit a number of twists between said payout point and said takeup pointand providing a different direction of stranding of the twisted unit forindividual section lengths, said twisting means engaging said twistedunit at a point closer to said takeup point than to said payout point, asection of said twisted unit having the same direction of strandinghaving a minimum length which is the length between said takeup pointand the engagement point of said twisting means and a maximum lengthwhich is three times the length between said engagement point and saidpayout point.
 2. Apparatus as claimed in claim 1, wherein said twistingmeans is positioned as close as possible to said takeup point. 3.Apparatus as claimed in claim 1, wherein said twisted unit is strandedat said takeup point and one of the speed and direction of rotation ofsaid twisting means is regulated in accordance with the stranding atsaid takeup point during the passage through said twisting means of asection of said twisted unit having the same direction of stranding. 4.Apparatus as claimed in claim 3, wherein the regulation of said one ofsaid speed and direction of rotation provides stranding which is asconstant as possible over said entire section of said twisted unithaving the same direction of stranding.
 5. Apparatus as claimed in claim3, further comprising stranding means between said twisting means andsaid takeup point for stranding a plurality of twisted units, andwherein the regulation of said one of said speed and direction ofrotation provides resultant stranding of said stranding means of uniformsize and length.
 6. Apparatus as claimed in claim 1, wherein the speedof said twisting means is increased during the passage through saidtwisting means of a section of sAid twisted unit having the samedirection of stranding.
 7. Apparatus as claimed in claim 1, wherein thespeed of said twisting means is varied during the passage through saidtwisting means of a section of said twisted unit having the samedirection of stranding.
 8. Apparatus as claimed in claim 1, wherein saidtwisting means rotated in a single direction during twisting of saidtwisted unit.
 9. Apparatus as claimed in claim 1, wherein said twistingmeans rotate intermittently in a single direction during twisting ofsaid twisted unit.
 10. Apparatus as claimed in claim 1, wherein saidtwisting means is rotated after reaching a specific minimum during thestranding of the section of the twisted unit.
 11. Apparatus as claimedin claim 1, wherein said twisting means is rotated and engages in anonpositive manner a length of twisted unit perpendicular to the axis ofsaid twisted unit preventing spreading thereof, the length of engagedtwisted unit being shorter than the length of twisted unit to be twistedin the direction of rotation of said twisting means.
 12. Apparatus asclaimed in claim 11, wherein said twisting means comprises spacedcomponents on both sides of said twisted unit and said componentscontact said twisted unit with a pressure which does not hinder thepassage of said twisted unit through said twisting means.
 13. Apparatusas claimed in claim 12, wherein said twisting means functions as a leverrelative to the axis of said twisted unit and transfers force to saidtwisted unit in the direction of rotation of said twisting means bydeflection of said twisted unit.
 14. Apparatus as claimed in claim 1,further comprising additional twisting means between said payout pointand said twisting means for providing homogeneous stranding of thesection of said twisted unit between said payout point and said twistingmeans.
 15. Apparatus as claimed in claim 14, wherein said twisting meansand said additional twisting means rotate in the same direction atincreasing speeds relative to the advancing of said twisted unit. 16.Apparatus as claimed in claim 15, wherein said twisting means comprisesthree spaced rollers mounted for coplanar rotation with their axespositioned in a manner whereby said twisted unit passes in contact witheach of said rollers in curvilinear fashion.
 17. A process for strandinga twisted unit of a cable in different directions of stranding forindividual lengths, comprising the steps of forming a twisted unit froma plurality of cable elements at a payout point; and twisting thetwisted unit in a nonpositive manner perpendicular to the axis of saidtwisted unit a number of twists at a point between the payout point anda takeup point and providing a different direction of stranding of thetwisted unit for individual section lengths when said twisted unit is instretched rotatable condition at a point closer to the takeup point thanto the payout point, a section of the twisted unit having the samedirection of stranding having a minimum length which is the lengthbetween the takeup point and the twisting point and a maximum lengthwhich is three times the length between the twisting point and thepayout point.
 18. A process as claimed in claim 17, wherein the distancebetween the takeup point and the twisting point is considerably smallerthan the distance between the twisting point and the payout point.
 19. Aprocess as claimed in claim 17, wherein the relation of the distancebetween the takeup point and the twisting point and the distance betweenthe twisting point and the payout point is varied.
 20. A process asclaimed in claim 17, further comprising stranding a plurality of twistedtwisted units, each twisted by twisting a corresponding one of aplurality of twisted units.
 21. A process as claimed in claim 20,wherein each of the twisted units is twisted at a varying one of speedand direction of rotation, the variation of twisting occurring at a timedifferent from that of the otHers.
 22. A process as claimed in claim 20,wherein each of the twisted units is twisted at a different one of speedand direction of rotation from that of the others.
 23. A process asclaimed in claim 20, wherein each of the twisted units is twisted at atwist point a distance from a corresponding takeup point and a distancefrom a corresponding payout point which have a different relation toeach other from the others.